Known conventionally as this type of integrated optical device are those described in patent literature 1 and patent literature 2.
The device described in patent literature 1 is provided with an optical power attenuator of a shutter type and an optical power monitor. Moreover, it is configured to attenuate at the optical power attenuator a light incident from an optical fiber on an input side, emit the attenuated light from an optical fiber on an output side, and detect at the optical power monitor a quantity of this light.
Furthermore, the device described in patent literature 2 is a tunable filter configured to diffract at a diffraction element a light incident from an optical fiber on an input side into a plurality of wavelength components and, by reflecting by a mirror a light of a desired wavelength component in an emission direction, emit this light from an optical fiber on an output side.
Furthermore, patent literature 2 describes not only how, by controlling a reflection angle of the mirror around two orthogonal axes, a wavelength of the light emitted from the optical fiber on the output side can be varied but also how the device can be made to function as an optical power attenuator by controlling a quantity of the light reflected at the mirror.